1. Field of the Invention
The invention relates to an improved semiconductor manufacturing device in which SEL(State Excited by Light) effect can be enjoyed.
2. Prior Art
There have been known processing techniques for semiconductor device comprising a substrate and nonmonocrystalline semiconductor layer formed on the substrate. In many products according to such techniques, some undesirable effects are observed. Namely, immediately after fabrication, a highly purified semiconductor exhibits decrease of conductivity under photo annealing in atmospheric air whereas it recovers by virtue of thermal annealing. The effect appears repeatedly. The inventors have found that such phenomenon, called Staebler-Wronski effect, is observed only on semiconductors taken out from a vacuum chamber and placed in contact with atmosphere.
Not only repetition of increase and decrease in conductivity, the conductivity tends to gradually decrease as repeating Staebler-Wronski effect. This is undesirable especially in semiconductors applied to solar cells.